Gas-to-Oil Ratio on a Lawn-Boy

Two-cycle gas engines that power Lawn-Boy walk-behind mowers are lightweight and powerful, but you need to mix oil with gas. The Toro Company of Bloomington, Minnesota, the manufacturer of Lawn-Boy mowers, recommends 2-cycle motor oil made by Lawn-Boy, Toro or one of numerous 2-cycle motor oils that meets the TC-W3 standard of the National Marine Manufacturer’s Association. The gas-to-oil ratio varies by model and the year manufactured.

Gasoline to Use

Lawn-Boy recommends using gasoline that is 87 octane or close to it. Using higher-octane gas doesn’t add anything useful and some brands contain additives that are harmful to small engines. Gas with up to 10 percent ethanol alcohol is okay. Only buy gas that you will use within one month or add a fuel stabilizer that will keep gas fresh from four to six months. You can buy fuel stabilizers at most dealers of small engines.

Models with a 32-to-1 Ratio

Add one 4-ounce can of recommended oil to 1 gallon of gasoline, a 32-to-1 gas to oil ratio, for these 2-cylinder Lawn-Boy models: A-10; A-11; A-12; C-10 through C-17; C-20 through C-22; C-40 through C-42; C-50 and C-51; C-60 and C-61; C-70 through C-78; C-80 and C-81.

Ratio by Date of Manufacture

For some Lawn-Boy models, the recommended ratio of gas to oil depends on the date it was manufactured. Add one can of lubricant per 1 gallon of gas for these models manufactured in 1971 or earlier: C-18 through C-19B; C-43 and C-44; D-400 through D-4008; D-405E through D-408E; D-430 and D-431; D-440 through D-448; D-445E through D-448E; D-450 through D-452; D-460 through D-462; D-475; D-480 and D-600. If those models were made in 1972 or later, add one can per 2 gallons of gas.

Ratio of Older D-Series

For D-series models manufactured between 1954 and 1977, add one can of lubricant for 2 gallons of gas. These models include D-409, D-433, D-449, D-463, D-476, D-481, D-601, D-601E, D-640, D-641 and D-642AE.